Abstract

This report has two main goals: (1) To present and compare the various procedures of risk assessment as they have been applied to liquefied energy gas (LEG) terminal siting, and in doing so to clarify the limits of knowledge and understanding of LEG risks. (2) To quantify and compare the risks at four LEG terminal sites, namely Eemshaven (Netherlands--NL), Mossmorran (United Kingdom-UK), Point Conception (USA), and Wilhelmshaven (Federal Republic of Germany--D).

The major findings of this report can be summarized as follows:

1. There is no unique concept of risk that is used throughout all the risk assessment reports examined in this study. Many of the important differences between the reports stem from the different risk concepts used. Some reports do not even define their underlying risk concepts. However, there is a concept of risk that involves several measures, each based on both probabilities of failures and consequences of failures, that is judged to be superior to other less comprehensive risk concepts.

2. The possible failures of the system, the probability of those failures and the estimation of their consequences to life and limb differ between the reports. Not all the differences can be explained by differences between the terminals and sites; some must be viewed as resulting from the limited knowledge and understanding of LEG risks. In this respect too little reference is made to remaining uncertainties in the estimation of risk in most reports.

3. Given the differences between the reports there is no relative tendency for each report individually to over- or underestimate the risk. Rather each report is more conservative on certain topics and less so on other topics as compared to the other reports. Thus no report can be singled out as producing a more conservative estimate of the risk (with respect to all parts of the total risk) than all the other reports.

4. On a relative risk scale it can be said that among the four sites Point Conception is the terminal with the lowest risk (because of very low population density), Mossmorran and Wilhelmshaven are the two terminals with the highest relative risk (because of high population density and more vessel traffic) and Eemshaven is in between. However, this does not imply anything at all about absolute risk.

5. Although risk is an important dimension of the decision to import LXG and to choose a specific site for the terminal, it should not be forgotten that other dimensions, like reliability, are important too. Any decision regarding LEG importation and terminal siting should involve comparisons with alternative options. As part of that process the risk of LEG should be compared with the risk of other options.

6. Whatever flaws the LEG risk assessments may have, they are clearly superior to less systematic ways to identify possible system weaknesses and inform the decision making process on the topic of risk.

This paper is the first part of a research report. The second part will specifically address the problem of giving guidelines to evaluate LEG terminal risk assessment reports and in particular to evaluate the risk assessment reports for the four terminal sites under study.